Nonmetric cranial variation of early modern human skeletal remains from Kumejima, Okinawa and the peopling of the Ryukyu Islands

Abstract

Nonmetric cranial variation of the Ryukyuans, including the Kumejima population, and their neighboring peoples was investigated. Among the populations compared, incidences of supernumerary ossicles in the Ryukyu series were high. The frequency of the supraorbital foramen of the Kumejima series was shown to be intermediate between those of the East Asians and Ainu. Mean measures of divergence (MMDs) based on 16 nonmetric traits showed that Kumejima is closest to Okinawa, Sakishima, and Amami, as well as to the Philippine and Yayoi groups. The four Ryukyu groups were the most distant from the Hawaii population. Multidimensional scaling and neighbor-joining methods were applied to the distance matrix to represent the relationships among populations. The four Ryukyu groups grouped together with the Yayoi to form a cluster, which was positioned between the East and Southeast Asians and the Jomon-Ainu populations. This suggests that there were not only northern, but also southern influences on the Ryukyu Islands during prehistoric and historic times, as suggested by recent genetic studies.